On Aug 7 2006, JoFa wrote:
> I do know it can show solids
> of revolution in 3-D which my limited drawing abilities cannot. I
> certain I don't NEED it. I just want to explore it.

Thank you. I wasn't questioning the use; in fact, what you mention is extremely
useful. I have used and taught computer programming and applications for around
30 years now, and would have killed [theoretically] for a program to show
rotating 3D vectors when teaching that.

Two programs spring to mind from what you say here. One is the symbolic algebra
[and graphing...] program, Mupad. There is also Maple, or Derive, but Mupad has
a free earlier version, or did have. Some schools where I live can afford such
programs provided by their board of education, so a lot might depend upon that
capability. I have a small collection of some freeware programs that do 3D
graphing as well, and they can get the point across, with appropriate lessons to
guide them, when other, more comprehensive material is not available.

I will be busy over the next few days, but will try to find time to supply a
list of possibilities. In the meantime, you might take a look here,

This material is based upon work supported by the
National Science Foundation under Grant DUE-0226284.
Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s)
and do not necessarily reflect the views of the
National Science Foundation.